1. Field of the Invention
The present invention relates to computerized numerical control (CNC) systems, and more particularly to a motion planning and interpolation processor having multiple microprocessors without shared memories and using Inmos transputer microprocessors.
2. Description of the Prior Art
Computerized numerical controllers (CNC) are utilized to control machine tools. A typical CNC is a complex system whose function it is to take a part program input and produce outputs that cause controlled motions of the controlled axes of machine tools and similar apparatus. The CNC system coordinates interaction with other aspects of its physical environment including analog and digital inputs and outputs to and from devices, sensors, and other subsystems, and interacts with operator oriented man machine interface devices as well as with data oriented devices such as part program storage, supervisory computer links, and the like.
A simplified block diagram of a typical prior art CNC is shown in FIG. 1 of the drawings. The part program describing the actions the CNC is to cause to be executed is prepared in a suitable format such as the EIA RS-274D programming standard on suitable media, such as 8 track punched tape, and read into the CNC by an input device, such as a punched tape reader. This tape is acted upon by the CNC processor which in turn controls servo motor drives and other devices that control the machine tool or other machinery controlled by the CNC. The system also includes sensors and other input and output devices, including those used by the operator and those associated with the machine tool and its support devices. The motion planning and interpolation functions of a CNC, in the past, been heavily based on shared memory, with the motion planning broken into parts and partial results passed via shared memory with the interpolation mechanisms accessing the final result and the real-time status of the system via shared memory. Message passing has also used, but is relatively slow and often based on shared memory in its implementation to avoid data recopying.
There is a need for a CNC processor element of a CNC that does not require shared memory and that can provide a looser coupled system with the performance of a close coupled system.
In recent years, multiple microprocessor architecture emphasizing fast, on-chip computation including on-chip multi-tasking and communication channels to other chips of the same architecture, has been developed which is applicable to state of the art CNC systems. A chip known as an "Inmos transputer (XP)" is the basis for such architecture. A typical chip is the Inmos T800. The present invention utilizes an Inmos transputer chip to provide an improved motion planning and interpolation element of a CNC.